The development of general and efficient chemical reactions provides the necessary tools for the design and synthesis of biologically and pharmaceutically important molecules. There has been a growing emphasis on developing practical methodologies for the synthesis of enantiomerically pure compounds, since enantiomeric isomers often exhibit different biological activities. Compared to a racemic mixture, the use of an enantiomerically pure compound improves the desired activity and reduces toxicity in addition to other clinical benefits. Consequently, the Food and Drug Administration requires the evaluation of both enantiomers of new chiral drugs before they can be submitted for approval. Among different approaches for preparing chiral non-racemic molecules, transition metal-based asymmetric catalysis offers promise for the development of cost-effective and environmentally benign methods. In today's pharmaceutical industry, where the market share of single enantiomer chiral drugs continues to rise, there are growing demands for new powerful stereoselective catalytic processes. Catalytic C-H amination via nitrene insertion represents one of the most important classes of chemical transformations. This type of catalytic nitrene transfer process provides a direct and general approach for the functionalization of C-H bonds in abundant hydrocarbons through stereoselective C-N bond formation. It serves as a valuable tool for the design and synthesis of biologically and pharmaceutically important chiral amine molecules. This research project is directed toward the development of new catalytic systems for stereoselective C-H amination reactions. For this particular proposal, we will focus on the utilization of cobalt(II) chiral porphyrin complexes [Co(II)(Por*)] as a class of new chiral catalyts to advance the enantioselective C-H amination reactions for stereoselective synthesis of valuable diamines and amino alcohols. These new catalytic methods will be applied to the stereoselective synthesis of biologically and pharmaceutically interesting nitrogen-containing molecules, including optically active amino acid-, diamino acid-, and fluoridated amino acid-based compounds that are antibiotics or tumor imaging agents. We hope these studies will ultimately lead to the development of practical Co(II)-based catalytic systems for general C-H amination reactions that can be successfully applied toward the stereoselective synthesis of biologically important natural products and pharmaceutically interesting small molecules.